How to Read an Aviation METAR — A Pilot-Friendly Breakdown

Learning how to read a METAR was, genuinely, one of the most frustrating parts of my private pilot training. Not because it’s complicated — it isn’t, once someone shows you the logic — but because every resource I found was either a one-line decoder that assumed I already knew what I was looking at, or a 60-page FAA document that buried the useful stuff somewhere around page 34. I printed out three different reference cards before my checkride. None of them survived a single cross-country flight in a sweaty kneeboard pocket. This is the guide I wanted back then, and the one I still reference when I’m rusty after time off.

METAR in 60 Seconds

Here’s a real METAR. Let’s pull it apart before we go any deeper.

METAR KBOS 121554Z 27018KT 10SM FEW045 BKN090 22/14 A2992 RMK AO2 SLP132 T02220139

That string of characters tells you almost everything you need to make a go/no-go decision, and once you know the format, you can decode any METAR from any airport in the US in under 30 seconds. Here’s what each chunk means, left to right:

• METAR — Report type. Routine observation. (SPECI means special, unscheduled — more on that later.)
• KBOS — ICAO station identifier. K prefix means US airport. Boston Logan in this case.
• 121554Z — Date and time. The 12th of the month, at 1554 UTC (Zulu). Always UTC. Always.
• 27018KT — Wind. From 270° (due west) at 18 knots.
• 10SM — Visibility. 10 statute miles. That’s the max reported in the US.
• FEW045 — Cloud layer. Few clouds at 4,500 feet AGL. The number is in hundreds of feet.
• BKN090 — Second cloud layer. Broken at 9,000 feet AGL.
• 22/14 — Temperature/dewpoint in Celsius. 22°C temp, 14°C dewpoint.
• A2992 — Altimeter setting. 29.92 inches of mercury.
• RMK AO2 SLP132 T02220139 — Remarks section. Automated station with precipitation sensor, sea-level pressure, and precise temp/dewpoint data.

The format never changes. Station, time, wind, visibility, weather, clouds, temp/dewpoint, altimeter, remarks. Lock that sequence in and you’ll never feel lost staring at a wall of letters again.

The Elements That Matter Most

Probably should have opened with this section, honestly. Before you memorize every code in existence, know which parts of the METAR are doing the heaviest lifting for your preflight decision-making.

Wind — The First Thing I Check

Wind affects your runway selection, your fuel burn, your approach, and if it’s gusty enough, your whole game plan. The wind group reads like this: direction in degrees magnetic, then speed in knots. If you see a G in the middle — like 27018G28KT — that’s gusts. This one is blowing from 270 at 18 knots, gusting to 28. That 10-knot spread is significant, especially in a light trainer. Anything over a 15-knot gust spread and I’m thinking hard about what I’m flying and where I’m landing.

Variable winds show up as VRB. VRB04KT means the wind is variable in direction at 4 knots — light and swirly. Not usually a problem. You’ll also sometimes see a variable wind direction group tacked on after the main wind group, like 250V310, which means the wind is varying between 250° and 310°. That one matters on a crosswind runway.

Visibility — What the Number Actually Means

In US METARs, visibility is reported in statute miles. 10SM is the ceiling on what gets reported — it doesn’t mean it’s exactly 10 miles, just that it’s at least that. Below 10SM, you’ll get values like 3SM, 1 1/2SM, or 1/4SM. That last one is serious. Quarter-mile visibility is essentially zero-zero conditions for most general aviation pilots.

When visibility drops below 6SM, you’ll also see a present weather group before the cloud report. Things like -RA (light rain), BR (mist), FG (fog), TSRA (thunderstorm with rain). These aren’t decoration. They tell you why the visibility is reduced.

Ceiling — The Number That Drives the Decision

The ceiling is the lowest broken (BKN) or overcast (OVC) layer. Not FEW. Not SCT. BKN or OVC. That’s what defines your ceiling for legal and practical purposes. A METAR showing FEW015 BKN080 has a ceiling of 8,000 feet, not 1,500 — even though there’s something at 1,500. FEW and SCT layers aren’t ceilings. They’re just clouds.

VFR minimums in Class G airspace require 1,000-foot ceiling and 3SM visibility during the day. Most pilots operating in controlled airspace are looking for considerably more margin than that. Personally, I won’t depart VFR into a forecast environment below 2,500 and 5SM unless I have a really compelling reason and a solid out.

Temperature and Dewpoint — More Than Just Numbers

The spread between temperature and dewpoint tells you a lot. Narrow spread — say, 2°C or less — means moisture is close to saturation. Fog, low clouds, and reduced visibility are likely, especially at night or in the early morning when temperatures drop toward the dewpoint. I’ve been fooled by a perfectly benign-looking afternoon METAR at a mountain airport, only to arrive two hours later in conditions that had fogged in completely because the spread closed after sunset. Lesson learned on that one — cost me a night at a $140/night motel in a town with one restaurant.

Temperature is also your density altitude alert. Hot day, high elevation, and you’re doing the math differently than on a standard sea-level winter morning.

Altimeter Setting — Don’t Skip It

Set it before you taxi. Set it again at the hold short. The altimeter setting in the METAR is what gets you in the ballpark. ATC will give you the current local setting, but if you’re flying into an uncontrolled field and self-announcing, you’re working off whatever the nearest ASOS reported. Within about 100nm, the METAR altimeter setting is close enough. Beyond that, you want a closer source.

Special Codes Pilots Miss

SPECI — When the Routine Isn’t Enough

METARs are issued on a routine schedule — once an hour at most automated stations, more frequently at busier airports. A SPECI is an unscheduled special observation triggered by a significant change in conditions. If visibility suddenly drops below 3SM, if a thunderstorm arrives or dissipates, if the ceiling drops below 3,000 feet — the system generates a SPECI automatically. If you’re checking weather and see a SPECI in the list, that’s the one you read first. It’s telling you something changed fast.

FEW vs SCT vs BKN vs OVC — Get This Right

This trips up student pilots constantly. Cloud coverage is reported in eighths of sky coverage called oktas.

• FEW — 1 to 2 oktas. A few clouds. Not a ceiling.
• SCT (Scattered) — 3 to 4 oktas. Not a ceiling either.
• BKN (Broken) — 5 to 7 oktas. This IS a ceiling.
• OVC (Overcast) — 8 oktas. Complete coverage. Ceiling.
• SKC or CLR — Sky clear. SKC is used at human-staffed stations, CLR at automated ones (means no clouds below 12,000 feet).

VV (vertical visibility) replaces cloud layers when the sky is obscured — like in heavy fog or smoke. VV004 means vertical visibility of 400 feet into the obscuration. That’s an IFR emergency for most of us.

The RMK Section — Where the Real Data Lives

Most pilots I flew with in training ignored the RMK section entirely. That’s a mistake. The remarks section is where automated stations flag important additions that don’t fit the standard format.

• AO1 — Automated station without a precipitation discriminator. It knows it’s precipitating but can’t tell you rain from snow.
• AO2 — Automated station with a precipitation discriminator. More reliable.
• SLP — Sea-level pressure in hectopascals/millibars. SLP132 means 1013.2 hPa. (Always prefix 9 or 10 — whichever gives a value closer to 1000 hPa.)
• TSNO — Thunderstorm information not available. If you see this at a destination in convective season, know that the METAR won’t tell you about nearby thunder.
• PK WND — Peak wind. PK WND 35055/1423 means a peak wind of 350° at 55 knots occurred at 14:23 Zulu. That’s a data point worth noting.
• PRESFR / PRESRR — Pressure falling rapidly / rising rapidly. Either one is a flag that something significant is happening meteorologically.

Quick Reference Decode Table

This is the section you print out. Laminate it. Tape it to your kneeboard. Whatever works. These are the codes that show up most often in everyday GA flying.

Report Type

• METAR — Routine hourly observation
• SPECI — Special unscheduled observation

Wind

• KT — Knots
• G — Gusts (e.g., 18G28KT)
• VRB — Variable direction
• 00000KT — Calm winds
• 250V310 — Wind varying between 250° and 310°

Visibility

• SM — Statute miles
• 10SM — 10 statute miles or more
• M1/4SM — Less than 1/4 statute mile

Present Weather

• RA — Rain
• SN — Snow
• DZ — Drizzle
• FG — Fog (visibility below 5/8 SM)
• BR — Mist (visibility 5/8 to 6 SM)
• HZ — Haze
• TS — Thunderstorm
• GR — Hail
• GS — Small hail or snow pellets
• FZRA — Freezing rain
• FZDZ — Freezing drizzle
• – prefix — Light intensity
• + prefix — Heavy intensity
• No prefix — Moderate intensity

Sky Condition

• SKC — Sky clear (human observation)
• CLR — Clear below 12,000 feet (automated)
• FEW — 1–2 oktas (not a ceiling)
• SCT — 3–4 oktas (not a ceiling)
• BKN — 5–7 oktas (ceiling)
• OVC — 8 oktas (ceiling)
• VV — Vertical visibility into obscuration
• CB — Cumulonimbus (appended to cloud group, e.g., BKN040CB)
• TCU — Towering cumulus

Temperature and Dewpoint

• Format: TT/DD in Celsius
• M prefix — Minus (below zero). M05/M12 = -5°C / -12°C

Altimeter

• A — Inches of mercury (US format, e.g., A2992)
• Q — Hectopascals (international format, e.g., Q1013)

Common Remarks Codes

• AO1 — Automated, no precipitation type sensor
• AO2 — Automated, with precipitation type sensor
• SLP — Sea-level pressure (hPa)
• PK WND — Peak wind direction, speed, and time
• WSHFT — Wind shift (followed by time)
• PRESFR — Pressure falling rapidly
• PRESRR — Pressure rising rapidly
• TSNO — Thunderstorm detection not available
• FZRANO — Freezing rain sensor not operating
• $ — System needs maintenance (at the very end of a METAR — don’t ignore this one)

Frustrated by years of laminated cards that wore through after six months,